Return 415 if content type is not supported

[nflaig]

I am running some interop tests with Lodestar <> Grandine on a feature branch of Lodestar which uses ssz for almost all apis. I noticed that Grandine does complain about the unsupported content type (as expected) but it returns a 400 error instead of 415.

May-27 18:51:01.289[]                �[31merror�[39m: Failed to download SyncDuties epoch=0 - getSyncCommitteeDuties failed with status 400: invalid validator index: Expected request with `Content-Type: application/json`: Expected request with `Content-Type: application/json`
Error: getSyncCommitteeDuties failed with status 400: invalid validator index: Expected request with `Content-Type: application/json`: Expected request with `Content-Type: application/json`

On the Lodestar side, we check the status code, and if it's a 415 we would retry the request with JSON and cache that ssz is not supported for this route, but since Grandine return a 400 status code, the request just fails.

Note, we will use JSON by default if the spec does not specify that the API should support SSZ but it would still be great to have to fallback mechanism in place in case a user overrides the default behavior to always sent SSZ for all apis.

[Tumas]

hey @nflaig, did you have the chance to test this? Fix has been merged to develop.

[nflaig]

Do you have an image I can use?

[sauliusgrigaitis]

We don't build develop images, can you build it with the Dockerfile that is provided in the repo?

[nflaig]

We don't build develop images, can you build it with the Dockerfile that is provided in the repo?

It looks like EF devops builds an image from your dev branch, I can use that one https://hub.docker.com/layers/ethpandaops/grandine/develop-minimal/images/sha256-5135f0aa0bbc82c4ad487a01cea520a86f2d5c6f9a44d5abb191659e67695fda?context=explore

[nflaig]

Confirmed the fix by running the following config:

participants:
  - el_type: geth
    el_image: ethereum/client-go:stable
    cl_type: grandine
    cl_image: ethpandaops/grandine:develop-minimal
    vc_type: lodestar
    vc_image: nflaig/lodestar:post-validators
    vc_extra_params:
      - --http.requestWireFormat=ssz
    count: 4
network_params:
  genesis_delay: 60
  num_validator_keys_per_node: 64
additional_services:
  - assertoor
  - dora
snooper_enabled: true
disable_peer_scoring: true
assertoor_params:
  image: "ethpandaops/assertoor:master"
  run_stability_check: false
  run_block_proposal_check: false
  tests:
    - https://raw.githubusercontent.com/ethpandaops/assertoor-test/2a45f2f78dd2c336ac99bf15e61edc076f15ce67/assertoor-tests/block-proposal-check.yaml

Thanks for the fix 🙏